Mechanically resettable coulometer and timing device



Feb. 3, L. CORRSIN 3,493,860

I EECHANICALLY RESETTABLE COULOMETER AND TIMING DEVICE Filed Dec. 15; 1967 2 Sheets-Sheet 1 4 0/ 66 INVENTOR LESTER v CORRSIN ATTORNEY:

Feb. 3, 1970 I L. CORRSIN 3,493,359

' MECHANICALLY RESETTABLE COULOMETER AND TIMING DEVICE Filed Dec. l5. 1967 2 Sheets-$heet 2 INVENIOR LESTER CORRSIN BY W ATTORNEY United States Patent O 3,493,860 MECHANICALLY RESETTABLE COULOMETER AND TIMING DEVICE Lester Corrsin, 18 Wurts Ave., New Paltz, N.Y. 12561 Filed Dec. 15, 1967, Ser. No. 690,818 Int. Cl. G01r 27/22 US. Cl. 324-94 7 Claims ABSTRACT OF THE DISCLOSURE A mechanically resettable microcoulometer includes a mechanically actuatable pump preferably of the peristaltic type in the mercury passageway. Devices such as clock dials may be driven under control of the coulometers.

BRIEF SUMMARY OF THE INVENTION This invention relates to novel coulometric devices, and, more particularly, to novel microcoulometers including pumps to enable pre-setting and resetting the coulometers as desired.

Microcoulometers are known and have achieved a significant degree of commercial acceptance. Typical devices of this type are shown in US. Patents Nos. 3,045,178 and 3,316,376 to Corrsin, and 3,193,763 and 3,343,083 to Beusman. A typical microcoulometer includes a body of non-conductive material having a bore, preferably of capillary size, filled by two columns of mercury spaced apart by a drop of an electrolyte. Electrodes extend from opposite end portions of the bore through the wall of the body for connecting the two columns of mercury to an external electrical circuit. The device constitutes a miniature electrolytic cell, in which when a uni-directional current is passed through it, mercury from the column at the anodic end of the cell is dissolved in the electrolyte and plated out of the electrolyte onto the column at the cathodic end.

One important limitation of previous devices of this type has been the lack of an arrangement for quickly and conveniently adjusting their initial settings and for resetting them to predetermined reference positions. Heretofore, devices of this kind have been used either as single-use, throw-away devices, or as reversible devices that could be reset by the relatively slow electrolytic process, passing current through them in the reverse direction. There is a need in many utilizations to provide a device of this kind including simple and inexpensive means for resetting it rapidly and easily, preferably by mechanical actuation, to enable its use as, for example, an automatic timing device without the need for complex external control arrangements.

Briefly, the invention contemplates a microcoulometer in which the mercury circuit includes a closed loop portion with a pump disposed at a selected point along it. The pump itself, or some other means divides the mercury in the closed loop into two separate portions electrically insulated from each other. The mercury may be mechanically moved by the pump to re-set the coulometer as desired, and the pump has no effect on the normal operation. In the preferred embodiment, the pump is of the peristaltic type which does not require seals between moving parts.

DETAILED DESCRIPTION Representative embodiments of the invention will now be described in detail in connection with the accompanying drawing where:

FIGURE 1 is a plan view, partly in schematic form, and with certain conventional parts such as the supporting base, or frame removed, of a resettable coulometer according to the invention including a peristaltic type pump drivable by a manually reciprocatable member;

FIGURE 2 is a plan view, generally similar to the view of FIGURE 1, but showing a coulometer according to the invention including a peristaltic type pump drivable by a rotor;

FIGURE 3 is a plan view in schematic form of a clock controlled by the coulometer shown in FIGURE 2;

FIGURE 4 is a plan view, partly in schematic form, showing a resettable coulometer according to the invention including a piston pump;

FIGURE 5 is a plan view in schematic form showing a coulometer generally similar to that shown in FIGURE 1 but including an insulating liquid to separate the mercury columns, instead of the compression of the pump roller;

FIGURE 6 is a plan view in schematic form showing the application of the invention to a coulometer of the type having a stationary electrolyte and open-ended columns of mercury; and

FIGURE 7 is a schematic plan view of a coulometer according to the invention illustrating the use of a gear pump.

The coulometer shown in FIGURE 1 includes a closed loop mercury passageway (not separately designated) defined by a capillary tube 10 of glass or a rigid plastic material such as methyl methacrylate resin, and a flexible tube 12 connecting the opposite ends of the rigid tube 10. The rigid tube 10 is filled with mercury separated into two spaced columnar portions 14 and 16 by a drop of electrolyte 18, which may be, for example, an aqueous solution of potassium and mercuric iodides. The flexible tubing portion 12 is substantially entirely filled with mercury, which constitutes extensions of the columnar portions 14 and 16.

A peristaltic pump arrangement, generally designated 20, is arranged along a lengthwise portion of the flexible tube 12, both for pumping the mercury under manual control selectively backwards or forwards through the closed loop passageway, and for separating the mercury at the point where the roller 22 presses upon the tubing 12. As shown, the pump 20 includes a rigid backing plate 24, a first roller 26 arranged to roll along the backing plate 24, a second roller 22 in opposition to the first roller 26 and arranged to roll along the flexible tubing 12, and an expansible, spring loaded bracket 28 connecting the two rollers 22 and 26. The tubing 12 is disposed between the backing plate 24 and the contact roller 22. The spring loading of the expansible bracket 28 is made strong enough so that the tubing is normally held flatly compressed against the backing plate 24 by the contact roller 22.

When it is desired to reset the coulometer, the assembly of the rollers 22 and 26, along with the spring bracket 28 is simply moved along the backing plate 24 to force the mercury to the new position desired. The mercury may be moved unidirectionally, if desired, simply by retracting the contact roller 22 against the urging of the spring loaded bracket 28 and moving it to a new position of engagement against the flexible tubing 12.

Electrodes 30 and 32 are sealed through the walls of the tubing 10 or 12 in any desired manner for connecting the device to an energizing circuit (not shown).

A presently preferred embodiment of the invention is illustrated in FIGURE 2, which shows a construction essentially similar to the one shown in FIGURE 1, except that the peristaltic pump 40 is rotary rather than reciproeating. The peristaltic pump 40 includes a rotor 42, which carries a series of four contact rollers 44 equi-angularly spaced around its periphery, and which is disposed within a loop portion 46 of the flexible tubing 12. A curved backing plate 48 is used in this case disposed outside the loop portion 46 in opposition to the rotor 42. The mer cury in this form of the invention may be driven in either direction, as desired, by appropriate selection of the direction of the rotor 42.

FIGURE 3 illustrates a clock controlled by a coulometer according to the invention as shown in FIGURE 2. In this arrangement the rotor 42 is driven by a servomotor 50 through a gear train 52, which also drives a time indicator such as the clock dial 54 shown. The servomotor 50 operates in response to the output of a differential servo-amplifier 56, to keep the drop 18 of electrolyte always centered at a fixed reference position defined by a split photocell arrangement schematically indicated at In operation, as the electrolysis transfers mercury from one columnar portion 16 to the other portion 14, tending to drive the drop 18 of electrolyte to the right, for example, as viewed in FIGURE 3, the servo arrangement pumps the mercury in the opposite direction to keep the electrolyte drop 18 always in the same position, and simultaneously to drive the indicator 54. The pump 40 in this embodiment should be designed to provide a smooth pumping action so that rotation of the rotor is accurately responsive to the progress of the electrolysis. With modern microminiaturization techniques, the entire device shown in FIGURE 3, including a constant current energizing source for the electrolysis, could be incorporated within a housing very little larger than a heavy wrist watch.

FIGURE 4 illustrates an alternative modification of the invention in which a piston pump 60, generally similar in principle to a standard water pump, but miniature in form, and made of an insulating material, is included in the coulometer in place of the peristaltic pumps illus trated in FIGURES 1-3. Due to the surface tension of the mercury, a tight mechanical seal is not required between the handle 62 of the pump and the man housing 64, nor is one required between the piston 66 and the housing 64. Therefore, the pump may be made relatively inexpensively and easily assembled.

In the coulometers shown in FIGURES 1-4, the pumps serve not only to move the mercury to re-set the coulome' ters, but also to break the mercury in the closed loop circuits to prevent electrical shunting of the electrolytic cells. As shown in FIGURE 5, the latter function is not necessarily done by the pumps, but may be provided for by inserting a drop 70 of an insulating liquid such as an oil in the closed loop circuit. In this case, a pump 20 of the peristaltic type may be used, as shown, biased toward its disengaged position so that the flexible tubing 12 is not normally pinched, but only while the coulometer is being re-set.

FIGURE 6 illustrates thep ractice of the invention as applied to coulometers of the so-called free end, or fixed cell type as shown in Patent No. 3,316,376, in which the electrolyte is held at a fixed position, and the columns of mercury 14 and 16' are separated in a closed loop capillary 72 by an insulating fluid 74. For this type of conlometer, an auxiliary loop passageway is provided for the mercury, extending around the electrolytic cell 78, shunting the main capillary 72. A pump and means for breaking the column of mercury in the auxiliary passageway are provided along the auxiliary passageway.

The auxiliary passageway shown in FIGURE 6 is constituted by a flexible tube 76 leading from one of the main indicating columns 14 of mercury to the other column 16'. A pump 20, similar to the pump shown in FIGURE 1, is mounted along the tube 76 for manually resetting the coulometer by controllably transferring mercury between the columns 14 and 16' by mechanical action, bypassing the electrolytic cell 78.

FIGURE 7 illustrates the use of a small gear pump in place of the peristaltic and piston pumps shown in the other figures. In this case, also, the pump creates a gap in the column of mercury so that a separate insulator is not required to keep the two columns 14 and 16 of mercury apart.

What is claimed is:

1. In an electrolytic coulometer of the type including two bodies of mercury, an electrolyte between the bodies, and electrode means for connecting the bodies in an electrical circuit for electrolytic transfer of mercury between them, the improvement comprising means defining a passageway extending between the bodies of mercury and by-passing the electrolyte, liquid filling said passageway, and pump means disposed along said passageway for mechanically impelling liquid therein.

2. In an electrolytic coulometer of the type including two bodies of mercury, an electrolyte between the bodies, and electrode means for connecting the bodies in an electrical circuit for electrolytic transfer of mercury between them, the improvement comprising means defining a passageway extending between the bodies of mercury and by-passing the electrolyte, liquid filling said passageway, pump means disposed along said passageway for mechanically impelling liquid therein, and means along said passageway for electrically insulating the two bodies of mercury from each other.

3. The invention according to claim 2, wherein said liquid in said passageway is mercury, and said insulating means is constituted by said pump means.

4. The invention according to claim 2, wherein said liquid in said passageway includes an insulating liquid constituting said insulating means.

5. The invention according to claim 1, wherein said pump means includes a peristaltic pump.

6. The invention according to claim 1, wherein the electrolyte is maintained in a fixed position and the mercury bodies extend from the electrolyte towards each other along a closed loop path, and said passageway is in shunt with the closed loop path.

7. A coulometric timing device comprising an electrolytic coulometer of the mercury type including two bodies of mercury, an electrolyte between said bodies, electrode means for connecting said bodies in an electrical circuit for electrolytic transfer of mercury between them, means defining a passageway extending between said bodies and by-passing said electrolyte, liquid filling said passageway, pump means disposed along said passageway for mechanically impelling said liquid therein, means for sensing a transfer of mercury between said bodies, servo means responsive to said sensing means for driving said pump means to counteract transfers eitected electrolytically, and an indicator device driven by said servo means.

References Cited UNITED STATES PATENTS 3,045,178 7/1962 Corrsin 324--94 X 3,193,763 7/1965 Beusman 324--94 3,316,376 4/ 1967 Corrsin 32494 X 3,343,083 9/1967 Beusman 32494 WILLIAM F. LINDQUIST, Primary Examiner C. F. ROBERTS, Assistant Examiner US. Cl. X.R. 32468 

